A hard white bump on the finger joint may be gout, or it may be caused by tendon cysts, warts and other diseases. 1. Gout: Gout is considered to be caused by hyperuricemia and other factors, the patient will appear in the joints of the growth of gout stones, joint pain, redness and swelling and other symptoms, which will lead to the emergence of finger joints protruding white hard lumps phenomenon. 2. Tendon sheath cysts: tendon sheath cysts are considered to be caused by the degeneration or injury of the adjacent tissues, the patient is mainly manifested as a hemispherical bulge in the subcutaneous, mild pain and joint movement disorders, which will lead to the emergence of finger joints raised a white hard lumps of symptoms. 3. acromegaly: acromegaly is caused by human papilloma virus infection, the patient will appear in the affected area of white or light pink bumps, pain, bleeding and other symptoms, which will lead to the patient has a finger joints raised a hard white bumps performance. If you have a white bump on your knuckle, you should seek medical attention to identify the cause of the problem and treat it under the guidance of your doctor.